The present invention relates to carbon nanotube producing systems. More specifically, the present invention is directed to a carbon nanotube trapping apparatus and method, and a carbon nanotube producing system and method.
Carbon nanotubes are hollow cylinders of carbon atoms. Their appearance is that of rolled tubes of graphite, such that their walls are hexagonal carbon rings, and they are often formed in large bundles.
With the possession of metallic conductivity and semiconductor conductivity according to structures, carbon nanotubes are now top candidate to be applied to various technological fields such as, for example, electrodes of electrochemical storage devices (e.g., secondary cells or supercapacitors), electromagnetic shielding, field emission displays or gas sensors.
In recent years, methods for producing carbon nanotubes are classified into five to six categories such as laser discharge, laser deposition, and pyrolysis chemical vapor deposition (pyrolysis CVD). Especially, the pyrolysis CVD is being used mainly. In the pyrolysis CVD, carbon nanotubes grow on a metal catalyst while supplying a carbonic gas into a high-temperature reaction tube. The pyrolysis CVD is performed with metal catalyst particles at a temperature ranging from 600 to 1000 degrees centigrade. The carbon nanotubes growing on a metal catalyst produced in a high-temperature reaction tube are collected using a back filter installed on an exhaust line.
However, a carbon nanotube collecting method using a back filter encounters a decreased collection performance because holes of the back filter are clogged. Therefore, the apertures of the back filter should be unclogged periodically using a gas or a vibration plate. Since the back filter cannot be used at a high temperature, a cooling system should be installed at the front end of the back filter to cool an exhausted gas including a carbon nanotube below 200 degrees centigrade.